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Remarks on the Global Existence for Incompressible Navier-Stokes Equations

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Chinese Annals of Mathematics,Series B 2024年第4期45卷 529-536页

作者： sheng WANG Zexian ZHANG Yi zhou Shanghai Center for Mathematical Sciences Fudan UniversityShanghai 200433China School of Mathematics Science Fudan UniversityShanghai 200433China

In this article,the authors use the special structure of helicity for the threedimensional incompressible Navier-Stokes equations to construct a family of finite energy smooth solutions to the Navier-Stokes equations ... 详细信息

关键词： Navier-Stokes euqations Helicity Global existence Critical norm

Curve Classification Based onMean-Variance Feature Weighting and Its Application

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Computers, Materials & Continua 2024年第5期79卷 2465-2480页

作者： Zewen Zhang sheng zhou Chunzheng Cao School of Mathematics and Statistics Nanjing University of Information Science and TechnologyNanjing210044China Center for Applied Mathematics of Jiangsu Province Nanjing University of Information Science and TechnologyNanjing210044China

The classification of functional data has drawn much attention in recent *** main challenge is representing infinite-dimensional functional data by finite-dimensional features while utilizing those features to achieve better classification *** this paper,we propose a mean-variance-based(MV)feature weighting method for classifying functional data or functional *** the feature extraction stage,each sample curve is approximated by B-splines to transfer features to the coefficients of the spline *** that,a feature weighting approach based on statistical principles is introduced by comprehensively considering the between-class differences and within-class variations of the *** also introduce a scaling parameter to adjust the gap between the weights of *** new feature weighting approach can adaptively enhance noteworthy local features while mitigating the impact of confusing *** algorithms for feature weighted K-nearest neighbor and support vector machine classifiers are both ***,the new approach can be well integrated into existing functional data classifiers,such as the generalized functional linear model and functional linear discriminant analysis,resulting in a more accurate *** performance of the mean-variance-based classifiers is evaluated by simulation studies and real *** results show that the newfeatureweighting approach significantly improves the classification accuracy for complex functional data.

关键词： Functional data analysis classification feature weighting B-splines

Flexible nanoimprint lithography enables high-throughput manufacturing of bioinspired microstructures on warped substrates for efficient III-nitride optoelectronic devices

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Science Bulletin 2024年第13期69卷 2080-2088页

作者： Siyuan Cui Ke Sun Zhefu Liao Qianxi zhou Leonard Jin Conglong Jin Jiahui Hu Kuo-sheng Wen sheng Liu shengjun zhou Center for Photonics and Semiconductors School of Power and Mechanical EngineeringWuhan UniversityWuhan 430072China The Institute of Technological Sciences Wuhan UniversityWuhan 430072China Department of Mechanical and Mechatronics Engineering University of WaterlooWaterloo ONN2L 3G1Canada Jiangxi SMTC Semiconductor Co. Ltd.Nanchang 330096China

III-nitride materials are of great importance in the development of modern optoelectronics,but they have been limited over years by low light utilization rate and high dislocation densities in heteroepitaxial films grown on foreign substrate with limited refractive index contrast and large lattice ***,we demonstrate a paradigm of high-throughput manufacturing bioinspired microstructures on warped substrates by flexible nanoimprint lithography for promoting the light extraction *** design a flexible nanoimprinting mold of copolymer and a two-step etching process that enable high-efficiency fabrication of nanoimprinted compound-eye-like Al2.3 microstructure(NCAM)and nanoimprinted compound-eye-like SiO_(2.microstructure(NCSM)template,achieving a 6.4-fold increase in throughput and 2.%savings in economic costs over stepper projection *** to NCAM template,we find that the NCSM template can not only improve the light extraction capability,but also modulate the morphology of AlN nucleation layer and reduce the formation of misoriented GaN grains on the inclined sidewall of microstructures,which suppresses the dislocations generated during coalescence,resulting in 40%reduction in dislocation *** study provides a low-cost,high-quality,and high-throughput solution for manufacturing microstructures on warped surfaces of III-nitride optoelectronic devices.

关键词： Flexible nanoimprint lithography Bioinspired Micro-and nano-manufacturing III-nitride epitaxy Optoelectronic devices

Stochastic uncertain lubrication in gear transmission subjected to tribodynamic loading

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Friction 2024年第8期12卷 1741-1756页

作者： zhou CHEN Haiming SHA sheng LI Zheming TONG Shuiguang TONG State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China School of Mechanical Engineering Zhejiang UniversityHangzhou 310027China Wright State University 3640 Colonel Glenn HighwayDaytonOH 45435USA

A stochastic uncertain tribodynamic model is established for a spur gear pair for the first *** stochastic uncertainty of pinion rotation speed propagated to lubrication performance is *** probability density function of the minimum lubricant film thickness hmin evolves over time periodically at interval of an engagement *** between abrupt increase in meshing force and amplification of hmin uncertainty is *** and reliable lubrication performance can be achieved by suppressing the hmin uncertainty and decreasing the lubrication failure *** can be done by increasing lubricant viscosity,and decreasing input torque and uncertainty level of input rotation *** work lays a solid foundation for robust and reliability based optimization for tribodynamic gear system.

关键词： stochastic uncertainty gears elastohydrodynamic lubrication(EHL) tribodynamics

Experimental,Numerical,and Analytical Studies on the Bending of Mechanically Lined Pipe

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China Ocean Engineering 2024年第2期38卷 221-232页

作者： WEI Wen-bin YUAN Lin zhou Jia-sheng LIU Zheng State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China School of Civil Engineering Tianjin UniversityTianjin 300072China School of Mechanical Engineering Tianjin UniversityTianjin 300072China

Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion *** installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole *** this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical *** types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,*** hydraulic expansion and bending experiments of small-scale MLPs are *** addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive *** contrast,the liner of ALP remains intact without developing any wrinkling and collapse *** addition,a dedicated numerical framework and theoretical models were also *** was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.

关键词： lined pipe bending nonlinear ring theory buckling plasticity

A hybrid physics-informed data-driven neural network for CO_(2. storage in depleted shale reservoirs

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Petroleum Science 2024年第1期21卷 286-301页

作者： Yan-Wei Wang Zhen-Xue Dai Gui-sheng Wang Li Chen Yu-zhou Xia Yu-Hao zhou College of Construction Engineering Jilin UniversityChangchun130026JilinChina Institute of Intelligent Simulation and Early Warning for Subsurface Environment Jilin UniversityChangchun130026JilinChina School of Energy Resources China University of GeosciencesBeijing100083China Department of Safety Environmental Protection and Quality ManagementShengli OilfieldSinopecDongying257000ShandongChina Key Laboratory of Thermo-Fluid Science and Engineering of MOE School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an710049ShaanxiChina College of Computer Science and Technology China University of Petroleum(East China)Qingdao266580ShandongChina Department of Physics University of FribourgFribourg1700Switzerland

To reduce CO_(2. emissions in response to global climate change,shale reservoirs could be ideal candidates for long-term carbon geo-sequestration involving multi-scale transport ***,most current CO_(2. sequestration models do not adequately consider multiple transport ***,the evaluation of CO_(2. storage processes usually involves laborious and time-consuming numerical simulations unsuitable for practical prediction and *** this paper,an integrated model involving gas diffusion,adsorption,dissolution,slip flow,and Darcy flow is proposed to accurately characterize CO_(2. storage in depleted shale reservoirs,supporting the establishment of a training *** this basis,a hybrid physics-informed data-driven neural network(HPDNN)is developed as a deep learning surrogate for prediction and *** incorporating multiple sources of scientific knowledge,the HPDNN can be configured with limited simulation resources,significantly accelerating the forward and inversion ***,the HPDNN can more intelligently predict injection performance,precisely perform reservoir parameter inversion,and reasonably evaluate the CO_(2. storage capacity under complicated *** validation and test results demonstrate that the HPDNN can ensure high accuracy and strong robustness across an extensive applicability range when dealing with field data with multiple noise *** study has tremendous potential to replace traditional modeling tools for predicting and making decisions about CO_(2. storage projects in depleted shale reservoirs.

关键词： Deep learning Physics-informed data-driven neural network Depleted shale reservoirs CO_(2.storage Transport mechanisms

Geometric quality evaluation of three-dimensional printable concrete using computational fluid dynamics

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 963-976页

作者： Weijiu CUI Haijun SUN Jiangang zhou sheng WANG Xinyu SHI Yaxin TAO Department of Civil Engineering Qingdao University of TechnologyQingdao 266000China Innovation Institute for Sustainable Maritime Architecture Research and Technology Qingdao University of TechnologyQingdao 266000China Intelligent Construction Lab Qingdao University of TechnologyQingdao 266000China Shandong Zhaojin Industrial Development Co. Ltd.Yantai 264000China Architectural Engineering Institute Weifang Engineering Vocational CollegeWeifang 261000China Qingjian Group Co. Ltd.Qingdao 266000China College of Architecture and Urban Planning Qingdao University of TechnologyQingdao 266000China Department of Structural Engineering and Building Materials Ghent UniversityGhent 9000Belgium Institute of Building Materials ETH ZurichZurich 8064Switzerland

The importance of geometrical control of three dimensional(3D)printable concrete without the support of formwork is widely *** this study,a numerical model based on computational fluid dynamics was developed to evaluate the geometrical quality of a 3D printed *** numerical results were compared,using image analysis,with physical cross-sectional sawn *** influence of printing parameters(printing speed,nozzle height,and nozzle diameter)and the rheological behavior of printed materials(yield stress),on the geometrical quality of one printed layer was *** addition,the yield zone of the printed layer was analyzed,giving insights on the critical factors for geometrical control in 3D concrete *** indicated that the developed model can precisely describe the extrusion process,as well as the cross-sectional quality.

关键词： digital fabrication 3D concrete printing geometric quality computational fluid dynamics printing parameters yield stress

Biopsy forceps are useful for measuring esophageal varices in vitro

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World Journal of Gastrointestinal Surgery 2024年第2期16卷 539-545页

作者： Zhi-Hui Duan sheng-Yun zhou Endoscopy Center Xingtai People’s HospitalXingtai 054000Hebei ProvinceChina

BACKGROUND To avoid acute variceal bleeding in cirrhosis,current guidelines recommend screening for high-risk esophageal varices(EVs)by determining variceal size and identifying red wale ***,visual measurements of EV during routine endoscopy are often *** To determine whether biopsy forceps(BF)could be used as a reference to improve the accuracy of binary classification of variceal *** An in vitro self-made EV model with sizes ranging from 2.to 12.mm in diameter was *** online image-based survey comprising 11 endoscopic images of simulated EV without BF and 11 endoscopic images of EV with BF was assembled and sent to 84 *** endoscopists were blinded to the actual EV size and evaluated the 2. images in random *** The respondents included 48 academic and four private *** accuracy of EV size estimation was low in both the visual(13.81%)and BF-based(2..2.%)*** use of open forceps improved the ability of the endoscopists to correctly classify the varices by size(small≤5 mm,large>5 mm)from 71.85%to 82.17%(P<0.001).CONCLUSION BF may improve the accuracy of EV size assessment,and its use in clinical practice should be investigated.

关键词： Accuracy Liver cirrhosis Esophageal varices Endoscopy Measurement

Metal and ligand modification modulates the electrocatalytic HER,OER,and ORR activity of 2. conductive metal-organic frameworks

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Nano Research 2024年第9期17卷 7984-7990页

作者： Yanan zhou Li sheng Lanlan Chen Wenhui Zhao Wenhua Zhang Jinlong Yang School of Material Science and Chemical Engineering Institute of Mass SpectrometryNingbo UniversityNingbo 315211China Department of Chemical Physics University of Science and Technology of ChinaHefei 230026China Department of Material Science and Engineering University of Science and Technology of ChinaHefei 230026China Department of Physics Ningbo UniversityNingbo 315211China Hefei National Laboratory for Physical Sciences at the Microscale CAS Key Laboratory of Materials for Energy Conversion and Synergetic Innovation Centre of Quantum Information and Quantum PhysicsUniversity of Science and Technology of ChinaHefei 230026China

It is highly desirable to design efficient and stable hydrogen evolution reaction(HER)and oxygen evolution/reduction reaction(OER/ORR)electrocatalysts for the development of renewable energy ***,density functional theory(DFT)calculations were conducted to systematically investigate a series of TMN_(x)O_(4-x)-HTT(TM=Fe,Co,Ni,Ru,Rh,Pd,Ir and Pt;HTT=hexahydroxy tetraazanaphthotetraphene)analogs of two-dimensional(2.)conductive metal-organic frameworks(MOFs)as potential electrocatalysts for the HER,OER and *** thermodynamic and electrochemical stability simulations suggest that these designed catalysts are ***,CoO_(4)-HTT,RhN_(3)O_(1)-HTT and IrN3O1-HTT are predicted to be the most promising catalysts for the HER,OER and ORR,respectively,surpassing the catalytic activity of corresponding benchmark *** volcano plots were established based on the scaling relationship of adsorption Gibbs free energy of *** results reveal that regulating combinations of metal active centers and local coordination environments could effectively balance the interaction strength between intermediates and catalysts,thus achieving optimal catalytic *** findings not only opt for the promising HER/OER/ORR electrocatalysts but also guide the design of efficient electrocatalysts based on 2. MOFs materials.

关键词： hydrogen evolution reaction(HER) oxygen evolution/reduction reaction(OER/ORR) electrocatalysts design twodimensional(2.)conductive metal-organic frameworks(MOFs) density functional theory(DFT)